1. Field of the Invention
This invention relates to a mold assembly to be used for continuous casting, and more particularly to a continuous casting mold assembly which facilitates alteration of the width of the casting strip.
2. Background of the Invention
The molds which are used for continuous casting of steel slabs or the like generally have a basic construction which includes a pair of wide back-up frames, each with a wide copper plate fixed thereto, and a pair of narrow back-up frames, each with a narrow copper plate fixed thereto, wherein the narrow back-up frames are gripped securely between the wide back-up frames with the aid of a clamp actuator which is mounted on a clamp frame to retain the wide back-up frames in position.
In continuous casting, there often arises the need for changing the size of the continuously cast strip, especially the width of the continuously cast strip. In order to meet such needs, the molds are generally provided with a shift mechanism which moves the narrow back-up frames along the wide back-up frames when in an unclamped state. For example, shift mechanisms of this sort are known from U.S. Pat. Nos. 4,223,717, 4,516,622 and 4,523,623, which employ narrow frame shift motors mounted on clamp frames to drive screw shafts through a reducer for shifting of the narrow frame positions.
Further, since the wide and narrow copper plates are oscillated and kept in direct contact with the cast strip, such undergo abrasive wear in a short time period, thus necessitating the interuption of the casting operation for replacement of the mold.
For this purpose, it has been the general practice to provide a number of spare molds, each including reducers and screw shafts and drive motors for shifting the narrow mold walls in cooperation with an actuator for the wide frame clamp. These are inseparably mounted on the mold assembly of the conventional construction described above. This has been found to be very uneconomical.
In addition, since the actuator, motors and their adjunct parts have to be disconnected from sources of hydraulic pressure and electric power at the time of mold replacement, the mold assembly requires complicated maintenance procedures, with increased susceptiblities to the occurrence of problems.